JPS5830154B2 - Manufacturing method of porous stamp material using sintering method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is useful for stamp printing, printing circumference, personal stamps, store name plates, product name plates, and stamp rolls having a stamp part obtained by firing thermoplastic nidistomer powder. The present invention relates to a method for manufacturing a porous stamp material.

It has been known to impregnate a porous sintered body of thermoplastic elastomer with an ink liquid and use it for printing materials such as ink rolls and stamp pads.

The sintered porous body in this case is generally manufactured using thermoplastic elastomer powder with a particle size of 5□ to 200 microns, and its porosity is 30% to 80%. Consists of a mono-structural organization.

In the known porous stamp material having an engraved part, the engraved part is attached to a support part to form a button, and the engraved part and the support part are made of the same material and have the same structure.

A conventional method and apparatus for obtaining a porous stamp material is shown in FIG. 1, for example.

In the figure, the powder 1 is filled or filled into the depression 2 for molding the stamping part of the mold 4, and is heated and compressed in the direction of the gap by the pressure head 3, thereby obtaining a sintered porous body 5 for a stamp material.

The stamp material thus obtained has the following drawbacks. That is, (a) In continuous printing, the ink density for the first few to several dozen printings is constant and then becomes constant.

This phenomenon always occurs after printing is stopped, and especially the first few times, too much ink comes out and ink smearing is likely to occur.

Mouth] The corner of the engraving is not clear.

...] When large and small characters are mixed, small engraved characters require more ink than large engraved characters.

2) Ink consumption during continuous printing tends to be high.

etc.

We investigated the cause of this kind of defect, studied ways to eliminate it, and completed the technology of the present invention.

The mechanism responsible for these defects is considered as follows.

That is, regarding item 13, according to microscopic observation, the engraved surface part and the engraved surface part support layer are typically 1 as shown in FIG.
and 2, the stamped surface part 1 has the same texture as the stamped surface F, and has a rough texture with irregularities, both of which are made of small spheroidized powder. things as its constituent organizational elements.

The support layer 2 for the engraved surface part is also made of spheroidized Japanese dog-shaped powder, and has a rougher structure than the engraved surface part.

Therefore, at the start of printing, the ink liquid that had accumulated on the stamping surface and the part located close to the stamping surface of the stamping surface part 1 is rapidly consumed at the beginning, and then remains in the nearby area within the surface structure. The ink liquid slowly reaches the marking surface through the communication hole path and is finally consumed, and the ink liquid flows from the tissue located quite far away from the marking surface due to a certain amount of liquid friction in the capillary liquid passage. It passes through the pores with resistance, moves toward the stamped surface, and is finally consumed.

In this way, the ink liquid located on the marking surface of the granular structure and in the vicinity thereof immediately and in an excessive amount is useful for printing, but the liquid existing further inside passes through the thin tubes and is used to compensate for the friction that resists the liquid flow. It flows onto the surface and is consumed for printing at a constant flow rate of .

Therefore, the ink liquid that was initially supplied in large quantities and quickly,
As the number of times of printing increases, appropriate amounts are almost constantly supplied, and therefore, the disadvantage described in item (a) above occurs as a phenomenon.

Next, the disadvantage of item 9 is that the powder used during compression heating is sintered without being precisely and reliably spread over every corner of the concave mold.

Next, the drawback of item C) is that the sintering state of the powder for large letters and small letters is different.

That is, this is because the unevenness of small letters is more significant.

In addition, one of the reasons for this is that the conductive hole area behind the letters is comparatively larger in proportion to the narrowness of the lowercase letters.

The disadvantage of item 2) is that the pore size is too large.

In consideration of this defective mechanism, various experiments were conducted with the aim of resolving this problem, and a suitable manufacturing method was found here.

In the present invention, the male mold for molding the stamp material, that is, the mold having a convex portion, is made of commonly used metals, thermoplastic resins,
It may be manufactured by a conventional method using thermosetting resin, thermoplastic elastomer, rubber, or the like.

In addition, thermosetting resin,
Any material such as thermoplastic resin or metal can be used.

Fig. 3X shows flat male and female molds 1 and 3, and Fig. 3Y shows cylindrical molds 2 and 4.

Furthermore, thermoplastic nitrogen powders include powders of polyurethane, styrene-butadiene block copolymers, ethylene ethyl acrylate copolymers, ethylene vinyl acetate copolymers, and polyvinyl chloride plasticized with plasticizers, as well as powders derived from the above. These include pulverized porous powder, powder obtained by extracting a solvent from a thermoplastic elastomer solution, and nidistomer powder produced during the production process in a polymerization reaction.

In the present invention, the pressurization method is a conventional method, for example, as shown in FIG.
The convex plate 3 can be placed on the concave plate 1 and pressed between the press plates, or the convex plate 4 can be placed on the concave plate 2 in the case of FIG. 3Y and pressurized with an air bag or an oil bag.

This pressurizing method is not particularly limited to these methods.

Note that the layer 5 in FIG. 3X shows an example of pressure sintered powder.

One aspect of the structure of the stamp product obtained by this manufacturing method is schematically shown in FIG. 4, and the structure and effects of the present invention will be described below with reference to FIG.

The stamp material having the stamped portion shown in FIG. It is called.

) and layer side thin layer portion B1. C1, C2, D1 (hereinafter referred to as part B)
1. C1, C2°DI).

Now, a method for manufacturing a stamp material having this structure will be outlined below.

However, it goes without saying that the conditions of this manufacturing method vary somewhat depending on the physical properties of the powder used.

Heat deformation temperature range of 115℃ to 120℃ in the female mold recess,
Thermoplastic 1'lE with a particle size of 1 micron to 50 micron diameter
Fill with elastomer powder and use a male mold for forming the stamp material to 3.5
kg/(i pressure) for several minutes at a temperature within the range of 145° C. to 165° C. (this temperature varies depending on the type of thermoplastic nidistomer and its degree of polymerization) and sintering.

In this case, the powder may be preheated to a temperature close to the sintering temperature.

As a result, layer B, portion B1, and marking surface A are simultaneously formed.

At this time, since the surface texture of the stamped surface A and part B1 is a rough surface texture with unevenness of many small spheres derived from the powder used, the surface texture of the stamped surface A and part B1 is similar to that of the uneven and rough surface texture of a large number of small spheres derived from the powder used. The heating time is selected so that the surface texture is smooth and has few voids.

When the powder is heated and compressed, the powder on the stamped surface A and the side surface B1 directly contacts and is heated at a corresponding portion of the mold recess compared to other powders, so that the powder is spheroidized and further rolled. It becomes flat.

This rolling phenomenon can be achieved by properly controlling the heating time and forming a deep layer B.
It is necessary to do this so as not to reach the center part 1 of the area.

For this purpose, it is necessary to determine the necessary and sufficient heating time for the temperature according to the physical properties of the powder to be used, based on microscopic observation, and to strictly conduct heating within this time.

For example, if the appropriate heating time is 2 and a half minutes, and if the heating is only for 2 minutes, the engraved surface A and the side surface B
1 will have a rough porosity of the spherical body, and if heated for 6 minutes, the porosity of the inner casing of layer B will be too small, and the porosity will be too small under the optimum flow rate of the ink liquid. This leads to a phenomenon in which the shape is maintained as if the hole is too narrow to be used as a liquid passage channel.

For this reason, special consideration must be given to the temperature and time at which the powder is heated.

When performing scent printing, the manner in which the ink liquid in the layer B having an appropriate porosity is supplied in the direction of the marking surface is such that the marking surface A, which has a small porosity, acts in a controlled manner on the passing ink liquid. Excessive liquid transfer is not allowed, and the total area of the openings in the cross section of the pores in the stamping surface A is proportional to the total area.

Therefore, in this case, the undesirable phenomenon of printing being dark at the beginning and light at the middle can be avoided.

Next, layer C is formed in contact with layer B.

The same type of powder used for forming layer B, with a slightly coarse particle size, for example, a particle size distribution of 5 microns to 90 microns, is used in the recessed part on layer B, and the compression pressure is slightly lower than that used for forming layer B.
．． The layer C and the portion C1 are formed by processing and sintering under the same conditions as for forming the layer B at a pressure of 4 kP/i.

In forming this layer C, approximately 2 m711 of the powder is piled up and heated, compressed and sintered to simultaneously form a thin layer C2 having a thickness of 0.2 vtrtr& shown in the figure.

In the same manner, a layer and part D1 are formed using powder having a particle size of 20 to 200 microns at a pressure of 3.0 to 9/ffl.

In the stamp material obtained in this way, the porosity of the stamping surface A is the minimum, and the layer farther away from the stamping surface A is the immediate layer B.

The layers C and D have progressively larger porosity, and the amount of ink that can be contained within a unit volume of the layer decreases in this order.

In other words, the layer can contain a large amount of ink liquid, and the amount of ink liquid contained in the layer decreases as it goes to the upper layer, that is, as it approaches the stamping surface A, and the amount of ink liquid contained in the layer becomes minimal on the stamping surface A.

Therefore, during printing, the amount of ink liquid necessary and sufficient for printing that remains on the marking surface A and the amount of ink liquid sent and supplied from the layer B to the marking surface A are equally balanced.

Similarly, the amount of ink liquid supplied from layer C to layer B is balanced so as to be equal to the above-mentioned amount of supplied liquid.

In other words, when printing, considering the porosity, the lower layer,
The amount of ink liquid delivered to the marking surface A from C to B is constant, but the flow velocity in the flow hole gradually increases as it goes to the upper layer. As it approaches A, it increases, and finally reaches the marking surface A and reaches its maximum, and finally the ink liquid is consumed as characters on the object by printing.

In this exemplary embodiment, a stamp material consisting of three layers B, C, and D has been described, but a two-layer structure may also be used in order to save manufacturing labor.

However, the four-layer or five-layer structure allows the apparent density gradient, that is, the porosity gradient, which consistently exists between each layer of the stamping part, to be brought into a gentle relationship, thereby constantly supplying the ink liquid to the stamping surface A. can also be measured.

Furthermore, the compression pressure mentioned above is 2.5 kg/ffl to xo
It can be used in addition to ky/a, and it is preferable to increase this pressure as the height of the stamped surface is high.

In addition, this pressure may generally be lowered when the number of constituent layers is large or the thickness of the constituent layers is small, that is, when the layer thickness is small,
When increasing the number of layers, heating and compression makes it easier to carefully press the powder into every corner of the mold, and as a result, when stamping, it is possible to ensure the clarity of the print, that is, the sharpness of some corners. It is.

In Figure 4, the porosity of layers B, C, and D is approximately 30%, respectively.
It is around 40%, 50%, and the engraved surface is about 104
That of part B1 t Ct t C2t Dl is 20 respectively.
They are around 5, 22, 15, and 25.

It is preferable in terms of printability that the printing material has such a porosity distribution.

A stamp material having such a porosity distribution has a stamping surface A that is forced to come into contact with other substances each time during printing and transfers the retained ink liquid to other objects as characters, and B1 that does not transfer the retained ink liquid to other objects. Each part of C1, C2, and Dl is a husband-and-wife constituent layer B,
It is possible to hold a smaller amount of ink liquid than C and D.

Moreover, from the start of printing, a small amount of appropriate ink liquid is constantly removed from the marking surface A each time printing is performed, and therefore, there is no phenomenon of excessive ink liquid coming out at the beginning of printing, and there is no bleeding phenomenon and the ink liquid is consumed. By doing so, at the same time, B12 C1y
Each part of C2yDl is made of a material with low porosity and high apparent density, so during printing, a small amount of ink is maintained without dripping or loss. Ru.

This is truly desirable in terms of the functionality of the printing material.

According to the present invention, by manufacturing a stamp material having a support layer and a stamping surface portion consisting of two or more layers formed by filling a female mold recess and compressing and sintering thermoplastic elastomer powder,
As detailed above, the obtained stamp material suffers from various drawbacks seen in the conventional stamp materials, namely, excessive consumption of ink fluid due to the rapid flow of ink fluid during printing, and problems with the first few uses. This eliminates various drawbacks such as smearing, unclear marking corners, and the tendency to oversupply ink to small characters.

As described above, the porous stamp material product produced by the sintering method according to the present production method has achieved a significant improvement in printing performance compared to those produced by the conventional production method.

The present invention will be explained in more detail below using Examples.

Example 1 Powder having a consistency of around 50□Kron particle size obtained by crushing a thermoplastic nidistomer polyurethane resin (Nippon Elastolan E185 (trademark)) was placed in a concave part corresponding to the stamped part of an aluminum concave plate. After filling and preheating at 150℃ for 2 minutes, stacking the convex mold on the concave plate, 3.5 kg/2
One layer was formed by pressure firing at 152° C. for 2 minutes.

Next, a new layer of the same resin powder having an average particle size of 65 microns was filled, and a second layer was formed in contact with the above layer in the same manner as described above at a pressure of 3.4 kg.

Similarly, pressurization pressure 3.2 kg/ffl, particle size average 85
□The next third layer was formed using Chron powder.

Under the same conditions, the fourth layer was sintered and formed using powder with a particle size of 100 square meters at a pressure of 3.1 kg/7.

However, in forming the fourth layer, the powder is added to the entire layer and the excess is used to form a 0.2 mm thick layer between the shoulder of the convex part and the edge of the concave part by compression heating. I forced it.

The obtained product stamp material showed a porosity gradient of 15 to 58 1, with the porosity increasing layer by layer from the stamping surface to the lowest layer.

This product was lined with a polyethylene sintered sheet, incorporated into the marking part of a cash register, and a printing test was conducted after ink was injected.

As a result, (a) the printed outline of the corner of the stamped part was clear, and even the lowercase letters were clear with almost appropriate density.

(b) There was no change in the sharpness of the print between the initial and middle periods during the continuous printing operation.

Furthermore, no difference in print density was observed in mechanical printing.

Therefore, it is expected that in the future, it will be possible to easily produce porous stamping materials with markings with print density suitable for the application using this manufacturing method, and that this type of product will have further marketability in this industry. It was done.

This product also had excellent wear resistance and mechanical strength properties.

Although the gaps between the letters were narrow and dense, the ink liquid supply from the layer behind the stamped surface was sufficient and appropriate, and the print was clear.

Example 2 It was carried out according to the method of Example 1.

The filling compression heating was repeated 5 times.

The average hardness of the powders used was 50 microns, 70 microns, 70 microns, 75 microns, and 90 microns, respectively, and the pressure was 3.5 kg/c, 3.4 kynoi.
, 3.3ky/澹・3.3kg/crit,
It was 3.1 kg Apo.

The obtained stamp material had a structural organization in which the porosity in the five layers from the stamping surface to the support layer had a gradient from 16% to 70%.

Test printing was also performed on this product, except that the lowercase letters obtained were slightly darker than the large letters.
The same excellent and favorable results were obtained.

Example 3 According to the method of Example 1, Nippon Elastolan E185 (
E180 (trademark) powder (average particle size 7), which is softer than E180 (trademark)
5 micron) and heated to 4kg/cr? Compression and sintering layering was carried out at 3.5 ky/7, followed by filling and overlaying E180 powder (average particle size of 85 microns) and heating and compressing at 3.5 ky/7 to form sintered layers.

This was lined with a polyethylene sintered sheet and assembled into a hand-held spacer holder, and a printing test was conducted by varying the pressing force, but the same good results as in Example 1 were obtained for normal printing. .

In this case, we have also achieved particularly favorable results in that there is very little change in print density depending on the type of character compared to conventional products.

Example 4 Following the procedure of Example 2, preheating was performed to 145°C after powder filling.
, for 2 minutes, and under the same conditions as in Example 3, small letters were filled and compressed 4 times and large letters were filled 3 times, and the remaining recesses were filled with Nippon Elastolan E180, respectively, and then the same as in Example 3. The stamp material obtained was sintered according to the procedure and tested.

Good results similar to those of Example 3 were obtained, and uniform printing was achieved to such an extent that the difference in print density due to character type in Example 2 was not visually observable.

Example 5 The filled powder was preheated at 140° C. for 2 minutes, and the filling compression heating was repeated three times under the procedure and conditions of Example 2.

For small letters, use EI80 powder with average particle size of 75 microns, 85 microns, and 100 microns, and for large letters, use E1.
85 with an average particle size of 75 □, 85 micron, and 100 micron, and the compression pressure was 3.5 to 9/c.
I went to rit.

In addition, when forming the final layer, fill the concave plate with a top layer of 1 m7, compress it, and sinter at 150°C for 5 minutes to form a top layer of 1 m7.
After compression sintering, the 11-thick layer was compressed to form a layer with a thickness of 0.1 m771.

The obtained stamp material showed good test results similar to those of Example 3.

Example 6 It was carried out according to the method of Example 4.

When forming the final layer where the powder is piled up and compressed, before compression, a refined plain-woven gold cloth is layered on top and compressed in the same way. Even when external force was applied, the degree of distortion of the stamp surface was smaller than that of conventional products.

When this material was used for a printing belt for markings such as date stamps, it was found to be an excellent printing material.

Example 7 It was carried out according to Example 5.

Here, instead of adding powder, a 2mTt thick sheet that had been prepared by sintering E185 powder was added.
The material was compressed under a pressure of 5 kg/(-) and heated and sintered to obtain a useful printing material with excellent printing performance that is easy to attach to a surrounding plate having an ink storage portion.

Examples 8-14 Polyvinyl chloride powder (Zeon 121 (trademark)) 100
A mixture of 65 parts by weight of the plasticizer dioctyl phthalate and a small amount of a commonly used stabilizer was pulverized and dried, and the obtained powder was used to produce a stamp material according to the method of Examples 1 to 6. The manufactured stamp material obtained obtained obtained good test results as in the case where polyurethane was used as the powder.

All of the product printing materials in the above examples had excellent physical and mechanical properties and exhibited excellent printing functions.

[Brief explanation of drawings]

FIG. 1 is a schematic longitudinal sectional view of a stamp forming device on the stamp material side, which is equipped with a pressure head that compresses, heats, and sinters the powder on the recessed part of the female mold, and FIG. 2 shows the texture structure of the stamp surface. It is also a figure observed by a microscope showing the structure of the support layer on the surface of the stamp.
Fig. 3
Figure Y shows a longitudinal cross-sectional view of both male and female cylindrical molds. FIG. 4 is a vertical cross-sectional view of an exemplary schematic structural model of a porous stamp material produced by the sintering method according to the present invention. In the diagram, A... stamped surface thin layer sound IJB...
... layer, C ... layer, D ... layer, B1
... Side thin layer part of layer B, C1, C2...
... Side thin layer part of layer C, Dl ... Side thin layer part of layer.

Claims (1)

[Claims] 1. When molding a porous stamp material by filling a thermoplastic nystomer powder into a stamp molding recess on the stamp material side of a stamp material molding die and compressing it with a male stamp material molding die while heating, the thermoplastic elastomer powder is Layer formation by filling, heating, and firing is repeated at least twice to obtain a porous stamp material composed of at least two layers. At this time, in forming the layers, the particle size of the thermoplastic nidistomer powder used as the raw material increases as the distance from the stamp surface increases. The compression pressure value is set to be smaller as the distance from the stamping surface increases, and the forming layer has a larger porosity as the distance from the stamping surface increases. A method for producing a porous stamp material by a sintering method, characterized in that the porosity of the layer is made smaller than the porosity of the layer center body.